js 闭包和this实例

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做的闭包和this的几个测试实例：

var x = 2;function aa(){　　　　 function tt(){x=1;alert('this.x='+this.x+';x='+x);};return tt();　　 }   aa();//this.x=1;x=1

var x=2;var aa={x:1,bb:function(){return function(){return 'this.x='+this.x+';x='+x;};} } alert(aa.bb()());//this.x=2;x=2

var x=2;var aa={x:1,bb:function(){ var ss=this;return function(){return 'this.x='+ss.x+';x='+x;};} } alert(aa.bb()());//this.x=1;x=2

    var x=2;var aa={x:1,bb:function(){ x=3;var ss=this;return function(){return 'this.x='+ss.x+';x='+x;};} } alert(aa.bb()());//this.x=1;x=3

5. a

 var x=2;var bb=function(){x=10;return function(){x++;return 'x='+x;};    }var exam=bb();document.writeln('exam:'+exam()+exam()+exam()+';<br/>');var exam2=bb();document.writeln('exam2:'+exam2()+exam2()+exam2()+';<br/>');

value:exam:x=11 x=12 x=13;

exam2:x=11 x=12 x=13;

5.b

var x=2;var bb=function(){x=10;return function(){x++;return 'x='+x;};     }var exam=bb();var exam2=bb();document.writeln('exam:'+exam()+exam()+exam()+';<br/>');document.writeln('exam2:'+exam2()+exam2()+exam2()+';<br/>');

value:exam:x=11 x=12 x=13;
exam2:x=14 x=15 x=16;注意和5.a的区别